Atwood 10 gal Water Heater Wont Shut Off

[dano73]

So I've replaced the thermostat and eco, and the water heater will continue to heat the water until it is pouring out of the relief valve, when it is running on electric. This is the same thing it was doing before I reolaced them. I also can't get it to fire on propane any more, it will try to ignite, there is good spark, and there is power to the eco in and eco out when the ignitor is sparking. I read if there was power there, then the circuit board is good. It was working on gas till about a month ago, but I always shut it off manually, cause it wouldn't shut off at set temp. I guess the million dollar question is, why wont this thing shut off at the set temp?

[dano73]

Thanks for your help, I will test the relay tomw.

[enblethen]

You should be able to disconnect power and then thepower wire from relay contact pins. You should not have continuity if the relay is good. Bad relay would have continuity.
Should be able to just replace the relay. Open control box and get the exact part number.Relay

[dougrainer]

dano73 wrote:
Ok so if the relay is shot, what is the remedy? replacing the control board? And how would I go about testing that relay? And if that keeps the electric element on all the time, what prevents the propane from shutting off at the right temp?

IF there is 12 volts on the YELLOW wire coming out of the control board, THAT will keep the 120 relay engaged. If there is NO 12 volts on the yellow wire and the 120 element stays ON, the relay is bad---VERY RARE, I have NEVER seen one fail or stick closed.
The ONLY thing that will keep the LP ON is those 2 tstat's the ECO and the temp tstat. Either you miswired them or you have NOT replaced them correctly. The ECO(180 degrees), if you pull the wire off of it (either wire) it will kill power to the gas valve. If you pull either wire (brown) off of the main tstat(140 degrees), it will kill power to the control board. IF either tstat opens as it should, the control board CANNOT continue firing on LP,PERIOD. Doug

[dano73]

Ok so if the relay is shot, what is the remedy? replacing the control board? And how would I go about testing that relay? And if that keeps the electric element on all the time, what prevents the propane from shutting off at the right temp?

[enblethen]

look at diagram #12. It indicates there is a relay in your control box. If contacts are burnt together it will keep electric element on all the time.
Diagram